1. Field of the Invention
The present invention relates generally to tape cassettes for use in magnetic recording and reproducing apparatus, and more particularly, to a tape cassette of the type in which the tape is wound on and is guided between freely rotatable reels in the cassette housing. Specifically, the present invention is directed to improved elements for preventing undue slackness in the run of the tape extending across the opening of the casette housing when the casette is removed from the magnetic recording and/or reproducing apparatus and for providing automatic release of the run of the tape during recording and reproducing operation of such apparatus.
2. Description of the Prior Art
Tape cassettes for use in magnetic recording and/or reproducing apparatus are well known in the art. Particularly in the case of tape cassettes used in video recording and/or reproducing apparatus, it is necessary for proper recording and reproducing operations to withdraw the magnetic tape from within the cassette housing and to wrap or load the withdrawn tape about at least a portion of the periphery of the guide drum adjacent the rotary magnetic head which scans skewed record tracks on the tape as the tape is moved about the guide drum.
The required removal of the magnetic tape from within the cassette housing, however, creates several problems. When, for example, the tape cassette is loaded into a video recording and/or reproducing apparatus having an automatic loading device, the tape engaging member of the automatic loading device extends into the opening of the cassette housing to engage the tape. When the tape is engaged, the engaging member is actuated or moved in a path that extends out of the tape cassette housing and ends with the magnetic tape wrapped or loaded about the guide drum. Thus, the magnetic tape must be freely drawn out of the opening in the casette when the engaging member of the automatic loading device is operated. Moreover, the magnetic tape must be freely drawn out of the opening in the cassette during either the record or reproduction mode.
While the magnetic tape must be freely drawn out of the opening during either the loading, record, or reproduction mode, as described above, excessive looseness or slackness in the run of the magnetic tape is disadvantageous. Excessive looseness or slackness in the run of the magnetic tape causes the magnetic tape not to follow a substantially straight path between the guides provided within the cassette housing at opposite sides of the opening. Thus, the excessive looseness or slackness in the magnetic tape run causes the magnetic tape not to be properly engaged by the magnetic head or by the tape engaging member of the tape loading device, which often leads to damage of the magnetic tape or defective recording or reproducing operations. Moreover, excessive looseness or slackness of the magnetic tape often leads to damage of the extended run of magnetic tape during storage or non-use of the tape cassette.
There are several known approaches for preventing excessive looseness or slackness of the extended run of magnetic tape of the tape cassette. One approach is to provide the tape cassette or magazine with brakes for holding taut or preventing undue slackness in the run of magnetic tape. Such approach was disclosed in U.S. Pat. No. 2,894,700.
Another approach is disclosed in U.S. Pat. No. 3,797,779, assigned to the assignee of the present invention. In U.S. Pat. No. 3,797,779, as shown in FIGS. 1 to 3, slackening of the tape run T.sub.1 which traverses the opening 15 of the cassette housing 11 as a result of free turning of the tape reels 16, 17 within the cassette housing 11 when the cassette 10 is apart from the magnetic recording and/or reproducing apparatus, is avoided by providing resiliently flexible elements 24, 25, each being fixed at one end within the cassette housing 11. Specifically, resiliently flexible elements 25, 24 each have an end portion 25a or 24a cemented or otherwise suitably secured to partition 21 or 21', respectively, as shown in FIG. 2. Alternatively, resiliently flexible elements 25, 24a are secured by an adhesive provided on the end portions 25a, 24, respectively, as designated by reference numeral 18 in FIG. 4. The resiliently flexible elements 25, 24, in this case, are secured to the partitions 21, 21', respectively, by the peeling off of the release paper provided over adhesive portions 18 and by manually positioning and contacting the end portions 25a, 24a with the respective partitions 21, 21'.
After the resiliently flexible elements 25, 24 have been secured to the respective partitions 21, 21', the free ends of elements 25, 24 engage their respective portions of the tape between a respective one of the tape reels 16, 17 and the tape run T' for urging the respective tape portion into a relatively tortous path in which the tape is engaged by a fixed surface, which may be on guide members 26, 18, respectively. The tortuous paths impose an increased resistance to movement of the tape into the tape run. Each resiliently flexible element 25, 24 is deflected in response to tension in the respective engaged tape portion to permit the latter to follow a relatively less tortuous path in which the resistance to movement of the tape is reduced to free substantially the tape for transfer between the reels.
The use of the resiliently flexible elements 25, 24 to prevent excessive looseness or slackness of the extended run of magnetic tape of the tape cassette exhibits several major deficiencies. The fastening of the end portions 25a, 24a to the partitions 21, 21' is not reliable over a long time period primarily because of drying of the adhesive or cement used to fasten the end portions 25a, 24a to the partitions 21, 21'. The pressure, for example, finger pressure, used when the end portions 25a, 24a are fastened to the partitions 21, 21' inherently is not of a constant value from end portion to end portion. Leakage of adhesive or cement from the sides of the end portions 25a, 24a to the inside of the cassette causes contamination of the magnetic tape. Leakage of adhesive or cement is very difficult to prevent, especially over a long period of time. Exact positioning of the end portions 25a, 24a with the partitions 21, 21' when the end portions 25a, 24 are attached to the partitions 21, 26 is difficult to achieve. Because the end portions 25a, 24a must be exactly positioned with the partitions 21, 21', fabrication is not suitable for automatic machine assembly. In addition, the required fastening of the end portions 25a, 24a with the partitions 21, 21' is expensive to perform, and requires complex manual fabrication steps.